Process for making diallylidene pentaerythritol copolymers



United States Patent W PROCESS FOR MAKING DIALLYLIDENE PENTAERYTHRITOLCOPOLYMERS Werner Kern and Gino Dali Asta, Mainz (Rhine), Germany,assignors, by mesue assignments, to Hercules Powder Company, acorporation of Delaware No Drawing. Application Uctober 19, 1953 SerialNo. 387,042

Claims priority, application Germany December 17, 1952 2 Claims. (Cl.260-785) This invention relates to new resinous polymerization productsprepared from condensation products of com pounds having at least twoneighboring free alkylol groups and unsaturated aldehydes and to methodsfor the preparation thereof. These new resinous products may beadvantageously applied to many diiferent technical uses.

In accordance with the process of the invention, condensation productsof t p-unsaturated aldehydes or ketones with compounds containing atleast two neighboring free alkylol groups, are used as the monomer to besubmitted to polymerization with the use of a suitable catalyst.Particularly suitable for the preparation of condensation productscontaining one or more terminal vinyl groups are polyhydric alcohols,e.g. pentaerythritol, which contain alkylol groups attached to a centralcarbon atom. However, other alcohols, such as glycerin or erythritol,can also be used for the purpose. The methylol compounds can bepartially etherified or esterified. However, it is prerequisite for thepreparation for a siutable monomer that at least two neighboring freemethylol groups should be present. As monomeric initial material for theuse in synthetic resins, there may be used, for example, such productsas may be prepared according to German Patent 858,406 by reaction ofrip-unsaturated aldehydes with substances containing eventuallyesterified or etherified, but at least three free alkylol, particularlymethylol groups, attached to a central carbon atom, in presence ofacid-reacting substances at pH of about 35 and elevated temperatures,e.g., by treating trimethylolmethane or pentaerythritol with unsaturatedaldehydes.

Acrolein has been found to be particularly fitted as the aldehydeconstituent for the preparation of the monomer, since it leads todiallylidene compounds, which are particularly suitable for thepolymerization in accordance with the invention. Compounds such asa,fi-a1lylideneglycerin may also be used. However, particularly goodresults are obtained with diallylidene compounds, especiallydiallylidene pentaerythritol.

No polymerization products have hitherto been prepared from theabove-described compounds. It has now been found that for thepolymerization of these monomers, e.g., diallylidene pentaerythritol, ifone has in mind a rapid commencement of the reaction and the formationof technically valuable products in satisfactory yield, azo and diazocompounds form particularly suitable reaction accelerators, which, underthe usual polymerization conditions, form radicals on decomposition.Particularly good results are obtained on using azoisobutyronitrile andits homologs. Other derivatives of azoisobutyric acid and its homologs,e.g., the esters, can also be used in accordance with the process of theinvention. As azo or diazo compounds having the properties mentionedabove, there may also be named diazotized p-nitroaniline or6-benzoyl-amino-4-methoxy-n-toluidine, and, for lower polymerizationtemperatures, also diazothioethers, such as 4-methylbenzene-diazomercapto-2- naphthalene or the corresponding methoxy compound.

Patented Sept. 1, 1959 .1 varied in many respects by regulating thetemperature and the amount of catalyst. If azoisobutyronitrile is thecatalyst, it should generally be used in an amount Which does not exceed10 mol. percent, referred to the quantity of monomer. Preferably,however, a maximum of 3 mol. percent catalyst is used.

The resultant polymerizates are, in general, colorless and can be freedin a simple manner from the monomers, either by dissolving, particularlyin benzene, and subsequently precipitating with low-boiling gasolinefractions or by extraction. A particular advantage of the new productsconsists in the fact that, in general, they still contain a largeproportion (up to about 50%) of free double bonds which are avail-ablefor further reactions, especially for the preparation of mixedpolymerizates. By adding to the polymerization mixture otherpolymerizable substances or their mixtures, especially monomeric vinylacetate, diallyl phthalate or styrene, the properties of the resultingcopolymerizate may be further varied to fit the particular application.Maleic acid, preferably in small amounts, may also be used to vary theproperties of such products. It is further possible to add mixtures ofnatural resins and drying oils or their resinous modifications.

For the preparation of such mixed polymerizates and/ or polymerizatemixtures it is, of course, also feasible to use peroxides or redoxcatalyst systems, e.g., benzoyl peroxide and tertiary amines, as well asthe corresponding regulators and cocatalysts, or benzoylperoxide-ironacetylacetonate.

For the preparation of mixed polymerizates or polymerizate mixturesbased on =allylidene derivatives of polyalcohols, the polymerization canalso be carried out in two stages. In connection with this there is aprocedure by which it is very simple to direct the reaction, and whichinvolves polymerization of an allylidene derivative with an azocompound. This is followed by the addition of one or more monomers,together with the same or other catalysts, and the polymerization isthen carried to completion. In the preparation of the polymerizates inaccordance with the process of the invention, the polymerizationproducts were, as a rule, provided the catalyst contents were low,obtained in soluble form, and, as is more thoroughly described in theexamples, isolated from the monomers by precipitation. By using highercatalyst concentrations and, if necessary, higher temperatures, it isalso possible to obtain, if desired, practically insolublepolymerization products.

The synthetic resins obtained in accordance with the process of theinvention can be processed in the known manner, and can advantageouslybe shaped under pressure, e.g., by the injection molding process. Theyare suitable in general for the preparation of shaped bodies, forlacquer resins, adhesives, insulation, and for the manufacture ofartificial leathers.

The process of the invention is illustrated in the following:

Example I In order to prepare a synthetic resin in accordance with theprocess of the invention, 2.3 parts by weight (3 mol. percent)azoisobutyronitrile was dissolved in parts byweightdiallylidenepentaerythritol, after which the solutionwasheatedunder nitrogen in a sealed glass tube for three hours at 90 C. There wasobtained a viscous melt, from which the polymerizate was precipitatedwith thfijllSfiDfj benzine. Purification: of the resultingpolymerwasz'zefiectedi by. dissolving in .benzene'and precipitation with a1'0-fold amount of low-boiling gasolinev traction. @n .i'drying there rwas r obtained a completely colorless powdered r-product,'whichzissoluhle in a :large. .numberlof known solvents, e.g., benzene, acetone,carbonzitetrachloride, tetrahydrofnran. andiidimethylfoirnamide. 'Onthe'sother han'dsit is insolublein 'low boilinggasolinetfracti'ons,';methanol, diethyl ether and. water. The resin.-still contains .freeadouble: bonds capable of polymerization and canbe'fusedzby carefuleheating-to: 150.to:..1701.C.

IA Slmll21lip1OCll1Cll,:Wl1lGh meltsat Ca. 90 C. but ires'olidifies.above .this temperatmte, :can also "be-obtained withima polymerizationtime of 4f /21i hOlllS by.- increasingthep'olymerizationatemp'eratureto.i120v C.

Example 2 By-adding only 0.77 part'by weight (1 mol; percent)azoisobutyronitrile-=to 1100 parts by weight diallylidenepent-aeiythritol, there is obtained after 3 hours of.-poly merization at120 C. aviscous melt,-w-hich is-processed as in Example 1,.and whichyields .a colorless viscous polymerizate. The solubility propertiescorrespond'to those of the product described in the previous example,except that the melting temperature is lower, inasmuch as a colorlessmelt which can be'drawn into a thread is obtained by heating thepolymerizate to-40 to 50;C. This process is reversible and theresolidified'polymerizate remains soluble in the solvents mentioned inExample 1.

Example 3 .Byusing the same addition asdescribedin Example. 2, with,however, a polymerization temperatureof 60C. and a polymerization timeof 23 hours, there isobtained anequally colorless pulverizedpolymerizate. having the previouslydescribed solubility properties andstillmanitesting the presence ofdouble bonds which are capableofpolymerization. The polymerizate melts reversibly at 80 Cpwithout anyimpairment of the solubility.

Example 4 'For carrying out the polymerization in solution, 100 parts byweight diallylidene pentaerythritol together with 3.9 parts by weight (5mol. percent) of azoisobutyronit'rile were dissolved in 200 partsm-xylene, the operation being conducted at a temperature of 120 C. overa period of 3 hours. There resulted a viscous solution which, asinEXample 1, could be processed into an absolutely colorlesspolymerizate. This product, too, exhibits the solubility propertiesmentioned in the foregoing example and can be converted at 90l00 C. intoa colorless melt. which remains soluble in benzene afterresolidification.

A similar product is obtained by a 23-hour polymerization at60 C., theproperties corresponding to those described in the foregoing example.

vExample 5 By.means of a'23 hour polymerization at 60 'C.-with the useof 5 mol. percent azoisobutyronitrile, there is ob tained a viscous masswhich is only partially soluble in benzene. The benzene-insoluble.portion is also insoluble in other organic solvents and cannot be fusedor "softened by. heating to 260 C.

Example 6 *Byadding an additional 5'rnol. percent-of azoisobutyronitrileto the melt resulting in Example 1 and continuing the polymerization at60 C. for a period of 48 hours, there is obtained in approximately 100%conversion a practically. insoluble polymen'zate having propertiessimilar totthosedescribed in the foregoing example.

Example 7 In the preparation of mixed polymerizates there is' first usedin accordance with the procedure of Example 1, 1 mol. percent ofazoisobutyronitrile, resulting in a viscous melt, which is then reactedwith an additional 2.3 parts by weight ofvazoisobutyronitrile and 100parts by weight of styrene. Inthe second stage the'p'olymerizationtakesplace at 60 C. over a period of 14 /2 hours and results in a viscousopalescent -mass. The copolymerizatefis solnb'lein benzene and can beprecipitated from this .solution by mmns of low-boiling gasolinefractions into a powdered colorlesspolymerizate. which is free ofmonomers.

In place of the azoisobutyronitrile, 4 parts by weight benzoylperoxide'can also be used-inthe secondstep of the polymerization, theproduct being the same.

Similar results are obtained when 5 parts by weight of maleic acid .isadded-together with styrene to theproductof the first stage, and ifamixture of henzoylsper oxide. and trihexylamine is usedas catalystinthe second stage.

The two-step polymerization canalso be carried out "in the secondreaction stage, with;the use-of styrene-.as the, second componenttogether with-benzoyl peroxide, in such away as to prepare-insolubleproducts. In order to achieve :this, .it is sufficient to prolong thepolymerization time.

:Example 8 By one-stop polymerization of 100 parts by weightdiallylidene pentaerythritol, 100 parts byweight vinyl acetate. and 2.3parts by'weight azoisobutyronitrile there is obtained within 7 hours at60 C. 'a frothy gelatinous mass, containing in a highyield thecopolymerizate' of the two monomers. This polymerizate is insoluble inbenzene and yields, on'drying, a colorless powder.

'Diallyl phthalate can also beused instead of"vinyl acetate, theresulting copolymerizate, however, being 1 viscous and yellow.

A very rapid mixed polymerization ofdiallylidene' pentaerythritol andvinyl. acetate can be effected by using 3 mol. percent catalyst at C.After 25 minutes so many polymerization nuclei have been formed that thepolymerization takes place almost instantly, with considerable heatevolution, forming an insoluble mixed polymerizate.

Example '9 If styrene is used instead of vinyl acetate in the mixturedescribed in Example 8, there is obtained after a polymerization time of12 hours ahighly viscous melt which is readily soluble in benzene andwhich yields, on precip: itation with low-"boiling gasoline fractions, a.colorless, powdery 'polymerizate, soluble in the usual organicsolvents.

Example 10 Example 11 On proceeding as'in Example 1, but with apolymerization temperature of '60 C. -over'-a"-period--'of 130-hours,there is' obtained a benzene-soluble viscous 'melt. 0n polymerizing thisprepolymerizate with a solution 3 .55 parts by weightbenzoyl"peroxideinparts byweight of benzene, there is obtained after 100 hours at 60 C. anincrease in the polymerization yield.

Example 12 Diallylidene pentaerythritol can also be polymerized with theaid of azoisovaleronitrile. By maintaining the same reaction conditionsas described in Example 1, there is obtained in good yield, a reactiontime of 1% hours, a benzene-soluble polymerizate having the sameproperties as described in Example 1.

On prolonging the polymerization time for 2 hours, a large portion ofthe polymerizate becomes insoluble. Consequently, the polymerizationrate with this catalyst is even higher than with azoisobutyronitrile.

What we claim and desire to protect by Letters Patent is:

1. The process for the preparation of resinous addition copolymers whichcomprises heating diallylidene pentaerythritol and a compound selectedfrom the group consisting of vinyl acetate, diallyl phthalate, styreneand maleic acid in the presence of a free radical-producing catalyst toform an addition polymer.

2. The process for the preparation of resinous addition copolymers whichcomprises heating diallylidene pentaerythritol and a compound selectedfrom the group consisting of vinyl acetate, diallyl phthalate, styreneand maleic acid in the presence of a catalyst selected from the groupconsisting of azo compounds and diazo compounds which yield freeradicals by decomposition to form an addition ccpolymer.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Schulz et al.: Angewandte Chemie, vol. 62, No. 5, pp. 105,113, 114, 117, 118. (Copy in Sci. Libr.)

Schulz et al.: Angew. Chem. 62, pages 113 and 114 (1950). (Copy inScientific Library.)

1. THE PROCESS FOR THE PREPARATION OF RESINOUS ADDITION COPOLYMERS WHICHCOMPRISES HEATING DIALLYLIDENE PENTAERYTHRITOL AND A COMPOUND SELECTEDFROM THE GROUP CONSISTING OF VINYL ACETATE, DIALLY PHTHALATE, STYRENEAND MALEIC ACID IN THE PRESENCE OF A FREE RADICAL-PRODUCING CATALYST TOFORM ADDITION POLYMER.